Using Shared Virtual Memory Resources for Performing Memory-Mapping

• US 20150134930A1
• Filed: 11/09/2013
• Published: 05/14/2015
• Est. Priority Date: 11/09/2013
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Huang, Jian, Badam, Anirudh
• Granted Patent: US 9,612,973 B2
• Time in Patent Office: Days
• US Class Current: 711/206
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 2212/656 Address space sharing
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0673 Single storage device

Abstract

Functionality is described herein for memory-mapping an information unit (such as a file) into virtual memory by associating shared virtual memory resources with the information unit. The functionality then allows processes (or other entities) to interact with the information unit via the shared virtual memory resources, as opposed to duplicating separate private instances of the virtual memory resources for each process that requests access to the information unit. The functionality also uses a single level of address translation to convert virtual addresses to corresponding physical addresses. In one implementation, the information unit is stored on a bulk-erase type block storage device, such as a flash storage device; here, the single level of address translation incorporates any address mappings identified by wear-leveling and/or garbage collection processing, eliminating the need for the storage device to perform separate and independent address mappings.

Claims

1. A method, implemented by a computer system, for providing memory-mapped access to data items, comprising:

receiving a request from a first entity to access an information unit, as a memory-mapped resource;

creating shared virtual memory resources for use in interacting with data items provided by the information unit;

receiving a request from a second entity to access the same information unit, as a memory-mapped resource; and

associating the second entity with the same shared virtual memory resources.

2. The method of claim 1,

wherein the information unit is stored on an extended memory device,

wherein the extended memory device relies on a management process to determine locations at which data items are written on the extended memory device, and

wherein the computer system operates by using the shared virtual memory resources to perform translation of virtual addresses to physical addresses associated with locations on the extended memory device, said translation incorporating address mappings associated with the management process.

3. The method of claim 2, wherein the extended memory device is a bulk-erase type block storage device, and wherein the management process comprises wear-leveling and/or garbage collection.

4. The method of claim 1, wherein the shared virtual memory resources correspond to at least one self-contained memory (SCoMe) unit, each SCoMe unit having:

one or more SCoMe virtual memory regions; and

a table associated with each SCoMe virtual memory region, each table for use in translating virtual addresses that fall within an associated SCoMe virtual memory region into corresponding physical addresses.

5. The method of claim 4, further comprising:

receiving a virtual address that falls within one of the SCoMe virtual memory regions;

identifying an entry in a table that corresponds to the virtual address, the entry specifying a physical address;

determining whether the physical address corresponds to an address in main memory or an address in an extended memory device, to provide a determination result; and

accessing either a physical address in the main memory or a physical address in the extended memory device, based on the determination result.

6. A computer system for providing access to data items, comprising:

main memory for physically storing data items;

an extended memory device for also physically storing data items; and

a management system configured to;

provide shared virtual memory, selected from within a larger available region of virtual memory, for use in representing data items provided by at least one information unit;

provide a set of the shared tables for converting virtual addresses that fall within the shared virtual memory to physical addresses, the shared virtual memory and the corresponding set of shared tables corresponding to shared virtual memory resources; and

provide access, to at least two entities, to data items provided by said at least one information unit, via the shared virtual memory resources.

7. The computer system of claim 6, wherein the management system further provides non-shared virtual memory resources for use by each respective entity.

8. The computer system of claim 7, wherein an entity that links to the shared virtual memory resources does so via an instance of non-shared virtual memory resources associated with the entity.

9. The computer system of claim 8, wherein the instance of non-shared virtual memory resources includes permission information to define permissions associated with the entity, with respect to the shared virtual memory resources.

10. The computer system of claim 6, wherein the management system further comprises logic configured to:

copy at least a portion of a shared table to produce a forked table; and

assign different permissions to the forked table, compared to permissions associated with the shared table.

11. The computer system of claim 6, wherein:

the set of shared tables corresponds to a set of shared leaf page tables, and

an entity that utilizes a shared leaf page table links to the shared leaf page table via at least one higher-level page table,

said at least one higher-level page table being privately associated with the entity.

12. The computer system of claim 6, wherein:

the shared virtual memory resources include a plurality of self-contained memory (SCoMe) units,

each SCoMe unit is associated with a particular information unit,

each SCoMe unit identifies one or more SCoMe virtual memory regions, selected from the shared virtual memory, and

each SCoMe unit provides a shared table for each SCoMe virtual memory region, the shared table translating virtual addresses that fall within that SCoMe virtual memory region into corresponding physical addresses.

13. The computer system of claim 12, wherein:

the SCoMe virtual memory regions have a specified size, and

the management system is configured to allocate additional shared virtual memory to a SCoMe unit, when requested, in units of said specified size.

14. The computer system of claim 6, wherein the management system further includes a memory interaction module configured to:

receive a virtual address that falls within the shared virtual memory;

identify an entry in a table that corresponds to the virtual address, the entry specifying a physical address;

determine whether the physical address corresponds to an address in the main memory or an address in the extended memory device, to provide a determination result; and

access either a physical address in the main memory or a physical address in the extended memory device, based on the determination result.

15. The computer system of claim 6, wherein:

the extended memory device is bulk-erase type block storage device; and

the computer system is configured to use the shared virtual memory resources, in conjunction with non-shared virtual memory resources, to map a virtual address, identified by an entity, into a physical location within the bulk-erase type block storage device.

16. The computer system of claim 15, wherein the computer system further includes:

a wearing-leveling module configured to select locations at which data items are written in the bulk-erase type block storage device, to distribute the data items within the bulk-erase type block storage device based on a wear-leveling strategy; and

/or

a garbage collection module configured to select locations at which data items are written in the bulk-erase type block memory storage device, to facilitate erasure of blocks of data items in the bulk-erase type block storage device,

wherein the computer system, in mapping a virtual address to a physical location within the bulk-erase type block storage device, takes into account the locations selected by the wear-leveling module and/or the garbage collection module.

17. The computer system of claim 16, wherein:

the computer system includes an operating system, and

the wear-leveling module and the garbage collection module are implemented by the operating system.

18. A computer readable storage medium for storing computer readable information, the computer readable information providing a management system when executed by one or more processing devices, the computer readable information comprising:

shared virtual memory resources for shared use by entities, the shared virtual memory resources representing at least one information unit that has been memory-mapped into virtual memory;

non-shared virtual memory resources for non-shared use by each respective entity; and

an entity interaction module configured to allow plural entities to access said at least one information unit using the shared virtual memory resources,

the shared virtual memory resources incorporating address translation associated with wear-leveling and/or garbage collection.

19. The computer readable storage medium of claim 18, wherein:

the shared virtual memory resources include a plurality of self-contained memory (SCoMe) units,

each SCoMe unit is associated with a particular information unit,

each SCoMe unit identifies one or more SCoMe virtual memory regions, and

each SCoMe unit provides a table for each SCoMe virtual memory region, the table translating virtual addresses that fall within that SCoMe virtual memory region into corresponding physical addresses.

20. The computer readable storage medium of claim 18, wherein an entity that links to the shared virtual memory resources does so via an instance of non-shared virtual memory resources associated with the entity.